M-3 medium tanks stage an attack at Fort Knox in Kentucky, United States.

A film on the manufacture and uses of M-3 medium tanks in the United States. The headquarters of the armored forces of the nation at Fort Knox in Kentucky. A sign board reads: 'US Military Reservation, Danger, Keep Out, Range firing in this area Unauthorized persons entering this area, do so at their own risk, By order of the Commanding General'. Soldiers aboard tanks. The tanks move on the practice fields. A tower in the background. Smoke rises as the tanks fire. A ship in a harbor. Tanks loaded aboard the ship. Men work. The ship underway.